Why don't the U.S. military build heavy turret emplacements/automated towers?

[Archinist]

So, why don't the U.S. military build those massive turrets you usually see in RTS games? Or really any modern military, for that matter. I think there was some small .50 turrets built in some field somewhere a while ago, but those were only gun turrets with a little metal plating. Why don't they build massive turrets made out of concrete and steel with giant cannons attached to them?

[Simon_Jester]

Because they're expensive, they're heavy, they take months to build, they're vulnerable to modern weapons, and they're useless if the war you're fighting doesn't happen within ten or twenty miles of the place you built the turret.

Heavy turreted guns were a common feature of coastal defenses (because it takes big guns to sink armored warships attacking your port) from the late 1800s through the mid-1900s. They were less common on land, though. An army can usually simply walk around a fortress to get behind it; it doesn't have to sail past certain islands or straits to get to the place it's going. Only very important locations on land were protected by artillery turrets. Most of the time, if an army needed to defend a location they would simply take normal, mobile artillery guns, and park them in an open field. They might pile up dirt to protect the guns from exploding shell fragments or something, but it was rarely worth the trouble to build a concrete-and-steel fort to defend against a land army. It cost a lot of money, and it was pointless unless you knew the enemy would choose to attack that fortress during wartime.

Moreover, advances in artillery technology made it easier and easier for the enemy to construct siege guns that could penetrate the hardened roofs of a gun turret with huge exploding shells. Look up the German "Big Bertha" series of siege mortars for an example of this.

The last time anyone built major fortresses with reinforced concrete gun turrets was the 1930s, with the construction of the Maginot Line (a barrier of French fortresses on their border with Germany), and other, similar fortifications. That didn't turn out very well during World War Two.

For example, the Czechs built a huge defensive line in the mountains around their country to protect them from the Germans- then the international community pressured them into giving up that territory because it was inhabited by ethnic Germans and the Nazis claimed it on that basis. Waste of time and money.

The Belgians built a massive, mountainous fort called Eben Emael to protect one part of their country... the Germans landed several platoons of airborne troops on the fortress roof in gliders, who used fifty-kilogram demolition charges to shatter the fortress' guns.

Then the Germans went around the entire Maginot Line by attacking through an unfortified stretch of forest, neatly bypassing both the French fortresses and the French army (which had been waiting for them farther north). The Germans thus pierced into the heart of French territory, and after that it was all over and the French were forced to surrender within about a month. The expensive and massively built fortresses with their turrets, their underground bunker complexes, and their large garrisons of heavily armed troops were barely even attacked.

So it was widely believed that there wasn't much point in building heavy fortresses (concrete and steel in permanent structures, as opposed to temporary structures made from dirt, wood, and rubble to protect infantry against rifles, machine guns, and light artillery). People didn't do much of that during the war.
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Moreover, during World War Two, various powers invented "bunker buster" bombs that have heavy, armored nosecones, and which when dropped from a great height can penetrate huge thicknesses of dirt, rock, or concrete. These bombs can easily destroy dug-in fortifications, causing shock waves that collapse them and bury the defenders. And no turret roof, no matter how thick, can resist them. Since the turret can't dodge and isn't well enough armored to withstand aerial bombardment, it's doomed if the enemy decides it's worth the trouble to put it out of action.

They also invented shaped charge warheads that can be put on a missile (the same kind used to destroy tanks), and which can be easily carried by infantry and light vehicles... and which can punch through great thicknesses of concrete and steel, delivering a jet of plasma into the inside of an armored vehicle, turret, or bunker. Again, this makes it much less effective to layer large slabs of protection over things.

On top of all that, most major military powers now have nuclear bombs, and even if you did somehow build a fortress so strong it could not be broken into by troops and planes with conventional weapons, the enemy would easily be able to use nuclear weapons to wreck it. To make matters worse, to destroy the heavily armored turrets of your fortress the enemy is likely to use nuclear bombs that explode at ground level or punch into the ground and blow up underground. This means they will blast huge amounts of dirt and rubble into the air, which is now very radioactive- a ground-burst nuclear weapon creates lots of fallout, and the fallout will land on the countryside around the fortress. Your countryside, in other words.

Plus, since the war, the missiles and bombs that would easily make short work of armored gun emplacements have become guided, which means they are now highly accurate and will start hitting your gun emplacements in just a few shots. Since it won't take many shots to destroy the turret, that means that you're basically just spending millions of dollars on a turret that doesn't do anything to protect the weapons inside of it. You're better off using camouflage to hide your artillery and other heavy weapons in the open, and firing them when needed. Plus, that way you can take the guns you've positioned to defend one location, and move them to another location, or move them forward into enemy territory to launch an attack.

Even when armored turrets were common parts of fortresses, armies spent far more of their resources on mobile weapons of war that could be used anywhere they were needed, after all.

[Zixinus]

There is one thing that you could call an "automated turret" but it isn't meant to shoot at enemy crafts or soldiers, but incoming missiles. It's called the CIWS Phalanx, it's essentially a Gatling gun with radar and automated targeting. Of course I'm sure the thing can be controlled by hand and be able to do that sort of thing.

In modern times, it's a bad idea to build big stationary defenses like a turret-tower. If it can be seen from a great distance, it can be shot to hell with missiles and other heavy weapon fire. And unlike in video games, they are difficult to repair once they are shot.
Far better to have weaponry mounted to mobile vehicles that can be moved about as the battle changes.

[Lord Revan]

there's also the fact that recognization software isn't really up to the task where you could fully automate a turret and not have it accidently fire on your on men or civilians neither of which is desireble.

basically unlike in games turrets are expensive and don't really work anymore due to advances in technology if manned and if automated you're looking at massive PR crisis the moment some kid gets too close and is literally torn to shreads by the the turrets because the software precided a threat, that or the software is so cautious that the turrets won't trigger even if there was an enemy soldier nearby

to summerize, they're not worth the cost.

[Zixinus]

Actually, I just remembered that there is actually one such turret made: Super aEgis II. BBC article.. It is used in the Korean DMZ.

[Lord Revan]

Though the Korean DMZ is a place the targeting software isn't likely to get that many false positives.

[Zixinus]

Which is probably why they dared to do it. As of right now, the thing still requires a human to give firing permission on a target.

[Elheru Aran]

There is some potential for automatic smart-turrets like they had in Aliens; such things have already been or are being developed. Notably, they are portable to a certain degree.

As Simon covered very thoroughly up-thread, fixed positions are simply asking for trouble these days.

[SpottedKitty]

Though the Korean DMZ is a place the targeting software isn't likely to get that many false positives.

It's also a very, very specific scenario. In fact it's pretty much the only type of scenario in modern times where a fixed turret weapon like we're discussing might not be considered a hideously bad idea.

[Ace Pace]

Though the Korean DMZ is a place the targeting software isn't likely to get that many false positives.

It's also a very, very specific scenario. In fact it's pretty much the only type of scenario in modern times where a fixed turret weapon like we're discussing might not be considered a hideously bad idea.

There are actually a bunch of fixed turret weapons all over Israel's borders, mostly because the borders are quite static and the danger isn't an opposing army.

[Adam Reynolds]

Also, most of the "fixed" emplacements you find in RTS games are actually mobile in reality, to varrying degrees. I recall in Command and Conquer Generals that the US faction used the Patriot as a fixed emplacement, when it is truck mobile in reality, if requiring a bit of work to emplace. The GLA and Chinese merely used pillboxes of different types, and the Chinese also used a fixed gatling tower. I also love how all of those are equally effective against stealth aircraft.

The CIWS gun mentioned above also has a version that was used by the US Army against mortars in Iraq. It was at least better than nothing, but not much. They are also virtually useless against modern supersonic antiship missiles or artillery, as both are just too fast for the fragments to not shred whatever they would have otherwise hit anyway.

[Elheru Aran]

The CIWS gun mentioned above also has a version that was used by the US Army against mortars in Iraq. It was at least better than nothing, but not much. They are also virtually useless against modern supersonic antiship missiles or artillery, as both are just too fast for the fragments to not shred whatever they would have otherwise hit anyway.

Shrapnel is slightly better than a kaboom though, isn't it?

[TimothyC]

So, why don't the U.S. military build those massive turrets you usually see in RTS games? Or really any modern military, for that matter. I think there was some small .50 turrets built in some field somewhere a while ago, but those were only gun turrets with a little metal plating. Why don't they build massive turrets made out of concrete and steel with giant cannons attached to them?

Because if it can be seen, it can be hit, and if it can be hit, it can be killed. Fixed defenses of the kind you are talking about are mostly ablative in modern combat with few exceptions, and are a waste of money in the face of airpower.

[Simon_Jester]

I will also note that Archinist in his original post talked about heavy turrets, "massive turrets of concrete and steel with giant cannons." With the implication that he was picturing something like the artillery pieces mounted on a naval cruiser or battleship.

The answer is partly that giant cannons are themselves not very useful in modern war. Anything bigger than a six-inch gun has largely gone out of style, because anything you can't kill with a six-inch gun is worth expending a large missile on, and the missile will do a better job.

And partly that 'turrets,' in the sense of fixed weapon emplacements that cannot move, are usually not useful in modern warfare. Even if they're not automated and have a human crew (Archinist didn't say anything about the turrets having human crew or not), it doesn't matter, because they're still stationary targets. The enemy can pull out a pair of binoculars and work out exactly where they are years in advance, and you can't do anything to move the turret or conceal knowledge of its location. That means that any enemy with powerful weapons capable of knocking out the turret knows exactly where to shoot to do so, and will do so as literally their first move in a war. The turret will probably never even get a chance to shoot back.

Meanwhile, against enemies without powerful weapons, there just isn't much point to putting heavy weapons in a turret at all, because if you're fighting guerillas or light infantry, they'll just sneak and infiltrate, and you won't see them from far enough away to make it worthwhile to target them with heavy artillery. What you need to fight lightly armed enemies is lots of soldiers who can go around scouting out the terrain and finding the enemy, because once you've found them, having enough firepower to get rid of them isn't a problem. A stationary gun turret doesn't help with that goal.
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Final note: TimothyC used the word 'ablative,' I'm pretty sure what he means by that is that the defenses will predictably be destroyed, and all they do is buy a little extra time while the enemy burns through them. This is generally not worthwhile compared to spending the same amount of money equipping a mobile fighting force, which can stand and fight and harm the enemy, then retreat when the enemy's heavy weapons are targeted on them, and do it all over again the next day. Whereas the fixed defense line would simply be destroyed, and would never do you any good ever again.

[K. A. Pital]

So, why don't the U.S. military build those massive turrets you usually see in RTS games? Or really any modern military, for that matter. I think there was some small .50 turrets built in some field somewhere a while ago, but those were only gun turrets with a little metal plating. Why don't they build massive turrets made out of concrete and steel with giant cannons attached to them?

Because the usefulness of fixed defense emplacements (massive turrets with giant bunkers and guns) has steadily decreased since WWI through WWII and up to now.

The firing positions are immobile (cannot respond to a change in operative situation), they are hard to repair and easily destroyed by artillery strikes from afar because, well, they can't move.

The emphasis on mobility in warfare has steadily risen during the last century. Going back to fixed gun emplacements would be undoing like 50 years of war progress or more.

When the USSR scrapped most of its unfinished battleships after World War II and the Korean War (another piece of war machinery that's nigh useless when the enemy isn't a complete walkover), it placed the gun towers from the battleships in the Far East, on the coast near Vladivostok and to the north, to be used in case of nuclear war. These turrets had to hit enemy ships trying to land on the coast. At least in this case naval attack was the only thing they should've worried about. And even these things had very limited utility, as any fixed defense position does in our age.

[Sea Skimmer]

When the USSR scrapped most of its unfinished battleships after World War II and the Korean War (another piece of war machinery that's nigh useless when the enemy isn't a complete walkover), it placed the gun towers from the battleships in the Far East, on the coast near c and to the north, to be used in case of nuclear war. These turrets had to hit enemy ships trying to land on the coast. At least in this case naval attack was the only thing they should've worried about. And even these things had very limited utility, as any fixed defense position does in our age.

No new 305mm positions were built by the USSR after WW2 that I'm aware of, and none of the 16in guns were ever mounted for shore defense nor was any turret completed enough for this to have been a worthwhile prospect. All of the 305mm positions either date from Imperial Russian work, or the 1930s.

The 12in battery at Valavostock is No. 981 and was finished in the 1930s. If another exists what and where is it? Are you sure this is not in reference to the railroad gun batteries the city had? Hard to see why any new fixed sites would be built, by the late 1940s the guns were simply not powerful enough to deal with western battleships that still existed in considerable numbers. Nobody seems to know when the 14in railroad guns the USSR had were actually decommissioned, not surprising really considering one was kept hidden in a swamp-forest until the 1990s....

Turrets from Poltava were used to rearm Battery 30 at Sevastopol, which had had both turrets destroyed by Nazi 60cm mortar fire in 1942, but this was a direct replacement of war damage. Another 305mm battery at the city was not rearmed, its concrete work was actually newer from the 1930s rather then WW1 but was too extensively damaged. Finland had several similar 305mm turret batteries that remained in service until the 1980s, the Russian positions until 1994. Spanish 15in shore guns were last fired in 2008. On paper some of the Russian and Spanish positions are still serviceable.

The reason the Spanish kept the 15in guns so long was that they commanded the straight of Gibraltar, many others died earlier, and since that waterway is crowded and hemmed in by land and cities firing off anti ship missiles is a fairly risky proposition. That said the British had land based Except launchers at Gibraltar for a long time.

The Soviets did however build, as well as relocate some twin 180mm turret positions in several locations in the 1950s, but these guns are reported as having been issued with nuclear shells, and of course simply represent a much smaller scale of investment and firepower compared to battleship caliber weapons. A number of western countries built new similar cruiser caliber, batteries postwar too, though I believe none over 9.2in, and only then for certain Portugal which was given many British guns made surplus in 1956.

Communism did however build the most epic hardened coastal defense missile launcher battery ever (and one of few ever) near Sevastopol in the 1950s and 60s, 'Object 100" which originally had P-6 and later P-35 anti ship missiles. Two sites each with two twin launchers, rising vertical through armored doors. Absurdly stupid, but real cool.

[Sea Skimmer]

The CIWS gun mentioned above also has a version that was used by the US Army against mortars in Iraq. It was at least better than nothing, but not much. They are also virtually useless against modern supersonic antiship missiles or artillery, as both are just too fast for the fragments to not shred whatever they would have otherwise hit anyway.

Those Centurion Phalanx mounts are plenty mobile though. Everything is self contained on a single trailer. Lots of mobile AA guns still exist...now as seen below humanity has found ways to make mobile AA guns not so mobile, by putting them on top of skyscrapers but this is not exactly the same thing!

Shrapnel is slightly better than a kaboom though, isn't it?

The kaboom still happens though, the whole point of Phalanx is to explode the warhead and as close as 150m to the ship this can in some cases be worse because it will wreck all of the ships radar gear, instead of just some of it by acting as an air burst. Its probably still better to not be hit though, but the real problem is against supersonic targets Phalanx simply cannot carry out its 'burst-correction-burst' firing cycle on which it is dependent to be effective. It needs a certain amount of time to do that, its bullets only fly out so quickly. Against a mach 3 target Phalanx might not even open fire in time.

The solutions to this problem are to either increase firing density, which is how you get proposals in the west, and in the Soviet case actual adaption of twin galting gun mounts which do not use burst correction (just spam automatic fire) and weigh far far more, or to increase firing range and precision by using a guided missile.

The USN took that approach and it produced RAM, but RAM was delayed over a decade, and so Phalanx was produced in much larger numbers then ever intended. The existing mounts are still used because they are handy against unusual targets like boats and small drones, and because the actual radar on the mount is useful in its own right and now integrated with ship defenses (originally it was totally autonomous) and simply because they already exist as a sunk cost. But RAM launchers are replacing them more and more, and as soon as a laser weapon is perfected Phalanx will be dead.

As it was Phalanx was something of a panic reaction in its own right, which is why it was kept small, to go on existing ships, and used an existing gun instead of something far better. But its digital computers proved very hard to design in the 1960s and 70s and entry into service was highly delayed like basically every digital weapon system ever. But that wasn't known then!

For the land defense role Phalanx is nothing but a quick and expensive wartime band aid, and will be replaced in a couple years by the EAPS program missile project, now in live firing. Such a missile is going to be far far more effective, and entirely feasible as shown by Iron Dome (EAPS is rather smaller, and will have about half the effective range). A single Phalanx unit only had a 60-70% chance of intercepting a single rocket or mortar round at a time, requiring multiple units per base to have decent coverage against erratic insurgent attacks. EAPS is aiming to engage as many as 80 targets at a time, letting it actually counter massed rocket attacks from nation state forces, as well as being able to hit much higher performance targets like 155mm shells going ~mach 2 and up. Lasers will supplant EAPS.

[K. A. Pital]

When the USSR scrapped most of its unfinished battleships after World War II and the Korean War (another piece of war machinery that's nigh useless when the enemy isn't a complete walkover), it placed the gun towers from the battleships in the Far East, on the coast near c and to the north, to be used in case of nuclear war. These turrets had to hit enemy ships trying to land on the coast. At least in this case naval attack was the only thing they should've worried about. And even these things had very limited utility, as any fixed defense position does in our age.

No new 305mm positions were built by the USSR after WW2 that I'm aware of, and none of the 16in guns were ever mounted for shore defense nor was any turret completed enough for this to have been a worthwhile prospect. All of the 305mm positions either date from Imperial Russian work, or the 1930s.

The 12in battery at Valavostock is No. 981 and was finished in the 1930s. If another exists what and where is it? Are you sure this is not in reference to the railroad gun batteries the city had? Hard to see why any new fixed sites would be built, by the late 1940s the guns were simply not powerful enough to deal with western battleships that still existed in considerable numbers. Nobody seems to know when the 14in railroad guns the USSR had were actually decommissioned, not surprising really considering one was kept hidden in a swamp-forest until the 1990s....

I read about the SM-33 guns from the "Stalingrad" heavy cruisers being re-purposed for shore batteries. Yes, the 981 near Vladivostok was built before WWII, my bad - I confused this battery with the Sebastopol one which was finished after WWII (after 1948 even). Seems like using the "Stalingrad" guns for coastal defense wasn't followed up though, so I guess the USSR was also on its way to abandoning large-caliber fixed-emplacement artillery.

[Sea Skimmer]

It's really no surprise. It's one thing to keep guns you already paid for. Another to build huge new blockhouses ect.... the emplacements just end up too expensive. The USSR surely needed every pound of cement it had to build nuclear reactors and concrete runways for heavy bombers.

Traditionally the appeal of shore guns was that they were much much cheaper then warships, while also being less vulnerable by being small targets. Once you HAD to put them in armored turrets to avoid air attacks you lost too much of both advantages.

With small caliber guns where a turret could be built in a similar manner to that of tanks (rolled and welded, rather then big chunks forged and keyed together) and emplaced using normal types of construction equipment you could still justify it for key locations, all the more so when one turret gun replaced several existing open mounted guns, eliminating the crews as a long term cost. For battleship calibers everything is far more difficult, out of portion to the increase in raw weight. Just getting the guns to the battery can become a problem when you must move 100 ton loads by road with 1940s trucks.

Says something that the British with a whole global Empire to defend built no modern shore batteries over 9.2in between the 1880s and the 1930s, and only then emplaced five guns at Singapore, plus two more diverted to Dover by the fall of said island. Two twin 12in turrets batteries were started in WW1 to protect the Tyne, where a major shipyard was wide open to German battlecruiser raids but they used obsolete predreadnought turrets and really didn't make sense. One was never finished and the other scrapped after four years. The British instead in 1914 had the worlds largest submarine fleet, specifically for coastal defense. The war rather glaringly proved this was the right choice, and that Lord Fisher was a mad genius on most matters.

The US did begin a massive program of new coastal guns in WW2, but while involving no less then 27 two gun new batteries of 16 in guns, about half of which actually got finished, this was a replacement for something like 200+ battleship caliber guns and mortars in existing batteries all of which were to be scrapped. As it was most were scrapped by 1943 anyway to make more tanks.

Big problem is shore guns are basically purely a deterrent. You can make an unassailable strongpoint with them, but the enemy will just attack somewhere else as a result. In the battleship era it was handy not to have your naval bases bombarded, but aircraft rendered that goal moot. You can't actually expect shore guns to inflict serious losses on an enemy, the fortress duel is very rare, and one in which in actual combat shore guns tended not to live up to the hype. Meanwhile nearly any other use of money for coastal defense, say planes, subs, ships or even small caliber mobile guns can go and seek out the enemy, even if only over a limited radius.

The Komar missile boat is the Soviet replacement for battleship guns, and while it was highly vulnerable to air attack, at least it could die trying to do something!

[U.P. Cinnabar]

The Komar missile boat is the Soviet replacement for battleship guns, and while it was highly vulnerable to air attack, at least it could die trying to do something!

It made history, didn't it?

[Sea Skimmer]

Thinking a bit I'd figure heavy caliber shore guns were still valuable until about 1970, at which point smart weapons became too prolific for such guns to actually represent a serious defensive obstruction. Prior to that air attacks would have needed to be very large in scale, and thus at least represent diversions from other military tasks, to be effective. Against land based planes that wouldn't matter, but for carrier aircraft it's a big deal. By 1970 most of the worlds heavy cruisers and battleships were also gone, and while a fair number of ships with 6in guns lasted into the 1980s and even 90s in a few cases they could by nature be effectively engaged by 6in guns on land too.

As it is the worlds largest fortress guns remain US made 240mm weapons on Taiwanese islands, but they've have never had the equipment or training to engage moving ship targets. They have casemated bunkers that give a primary firing arc towards Chinese artillery positions, and the ability to be moved outside on railroad track to a open position for 360 degree field of fire. The guns are not modified from the original mobile configuration, but the Taiwanese don't keep the wheel axles or prime movers around anymore. The value is more political then anything else, since these guns were provided by the US in the 1950s in exchange for the Nationalists reducing the number of troops on the islands. That was to reduce the 'threat' of a Taiwanese INVASION OF MAINLAND CHINA. Because...yeah.

It made history, didn't it?

Yeah, but ironically in a situation in which the boats might as well have been shore based missile launchers.

The event was played up more then it really should have been in tactical terms, a lot of its significance came about only because the US had already cancelled the Mauler missile system two years earlier for budget reasons (its technical problems are more myth then reality), which had been intended for naval service specifically to stop this kind of threat (also it was an ABM system!).

No replacement had been launched because Vietnam War then consumed ALL THE MONEY, leading to a sudden ability of the USN to get panic reaction funding for multiple systems. One became BPDMS, later evolved into Sea Sparrow, the other was Phalanx, another super obscure one was Duel Mode Redeye, which was an attempt to make Redeye into something like RAM. That failed quick, and the idea was then moved to the much larger Sidewinder airframe and became RAM proper.

Which is a reason why I'm real dismissive of Phalanx whenever it comes up. Even from the get go something like RAM was supposed to be the real defense on new build ships! Phalanx was always a stop gap, and a weapon for ships which simply could carry nothing else, thus the 'bolt on' requirement with no system integration needed.

Meanwhile the Soviets certainly took this seriously, and the AK-630 system started around 1963. Much less advanced then Phalanx, but this was solved with MORE FIREPOWER, not just from using twin galting guns but a system which physically provided them with a huge amount of ammunition and ability to quickly reload. Heavy but it didn't need much computer.

The Euros meanwhile began Roland around the same time as AK-630, but it ended up taking an absurd amount of time because it was one of the first Franco-German defense procurement disasters and made US cost explosion events look tame, so the naval version never got anywhere. Germans bought US stuff, French ended up using Crotale which had actually started as an export weapon for South Africa, and now also the Mistral missile , which while MANPADS sized is a lot more advanced (aka expensive) then most MANPADS. Actually has a gyro based guidance system instead of a typical 'aim directly at the enemy' sort found in most such weapons that prevents them from being all that effective, shot for shot. Which is no big deal on land but fatal at sea.

Some other navies like Italy simply invested in better fire control gear for existing guns, 40mm and 76mm in their case. That approach was okay against Styx which only flew at 200ft, rather then say 20ft, in its early versions but hit some serious limitations against bigger and faster missiles and ones capable of true sea skimming flight paths (fragments wont kill warhead, direct hit unlikely, VT fuse won't work close to the water ect) which is why they also adapted Sea Sparrow and now have guided ammo for said cannon. Also much more advanced VT fuses only possible with 1980s+ electronics.

So the US got thrown into a revolution by the event of 1967 basically for budget reasons, while most everyone else just kept blundering forward on existing paths.

[U.P. Cinnabar]

Phalanx was always a stop gap

Like PIVAD was for the Army, after the failure of the Sergeant York system then.

Would Goalkeeper be considered in that same category of stopgap CIWS?

[Sea Skimmer]

Like PIVAD was for the Army, after the failure of the Sergeant York system then.

You have your decades mixed up. PIVAD and VADS, and the tracked version of HAWK were what the US Army bought collectively to replace the Mauler program. The US Army also considered several evolved versions of Mauler which would have added secondary IR guided missiles, so it could engage more targets at once, as well as versions in which 'slave' missile vehicles would serve alongside radar-missile vehicles, rather similar to the way the Soviets evolved the SA-6/11/17 system if on a smaller scale.

Functionally the 20mm-HAWK setup replaced the M42 Duster, which the US Army had intended to phase out with no gun armed replacement. Sergeant York and Roland were supposed to replace all of those systems in turn on the front lines, though HAWK was to be retained for rear area defense. When York was cancelled, and Roland reduced to a token force (in US hands, we paid for many systems manned by Germans to defend airfields) a new program was launched called Forward Light of Sight-Heavy which boiled down to an anti aircraft M1 tank with integral armored missile launchers (French VT1 missile was leading choice) and 35mm cannon but it never got past paper before the cold war ended. At which point the US Army concluded that the 25mm cannon on its thousands of Bradley's could handle emergency close range anti aircraft work, MEADS was launched to replace HAWK, and the Bradley Stinger became the AA missile vehicle...and that about brings us to now in terms of things that actually got hardware built.

Now though the Stinger Bradleys have all been converted in the last decade into IIRC, whatever we call the artillery observation Bradley, M7 I think. Leaving the Hummer Avenger, which existed as its own thing, for airborne forces and rear areas, as the only forward mobile air defense in the US military.

Would Goalkeeper be considered in that same category of stopgap CIWS?

It serves the same role as a last ditch defense, but no program wise it was much different. Goalkeeper was started much later in 1975, avoiding the early DIGITAL REVOLUTION OF PROBLEMS and is far larger and was never required to work on existing ships the way Phalanx absolutely had too. It was intended to be a major part of new build ships armament backstopping the automated NATO Sea Sparrow missile system, and was only retrofitted to a handful of larger vessels. British carriers are the only thing that comes to mind on that actually. The Type 22 was modded before construction of the relevant hulls to hold it.

However it typically was integrated with other ships defenses, over a decade before this was common for the improved models of Phalanx were tied into the Ship Self Defense System, which is basically AEGIS for ships that don't have SPY-1 radars and SM-2 missiles to worry about but shares no common hardware with AEGIS or NTU.

Compared to Phalanx Goalkeeper is about twice as heavy without ammunition, with much higher power and chilled water requirements. Vitally though, it is not bolt on. It penetrates the ships deck and stores its ammo drum below deck, with mounting bolts going into a second deck below that. That makes it much harder to install on any ship, and is the reason why functionally unless you weigh at least 20,000 tons you'll need to be designed to carry it from the get go.

Goalkeeper is actually heavier then the Italian 76mm SR gun everyone on the planet uses, though of course said system does not come with its own fire control, and the 76mm gun needs a big magazine below decks. But it's that kind of weight we are talking, so you can see why the Italians and many other navies simply went with improved 76mm guns!

Also to clear up some extremely common confusion online, Communist China does not use a clone of Goalkeeper. China instead uses a semi clone of the French SAMOS 30mm mount, which used the same GAU-8 gun from MERICA but was 100% different otherwise, and in some configurations did not have on mount search radar. France tested this system in the 1980s and judged it not worth the effort, precisely because of the realistic inability of any 20-30mm class cannon to deal with supersonic threats. So they sold at least one prototype to China in the late 1980s, alongside many other European and a few American war-kill technologies sold before Tiananmen Square.

The French instead upgraded Crotale further, created the Sadral version of Mistral as a closer range system, and got involved with what would become the Aster series missiles, which were originally tied into the most insane defense cooperation idea ever, the NATO Common Frigate Program. Which like 15 years later crapped out a couple of Horizon class frigates as a pure Franco-Italian program that still had THREE different versions. The APAR radar, WR-21 engine and several other programs are all other byproducts of that designed to fail, engineered to burn money concept.

[Col. Crackpot]

Simply, as Patton stated, "Fixed fortifications are a monument to the stupidity of man.". Translation: War is fluid and mobile. Mindless zerg rushes are for video games because real combatants are capable of creative thought.

[Highlord Laan]

So, why don't the U.S. military build those massive turrets you usually see in RTS games? Or really any modern military, for that matter. I think there was some small .50 turrets built in some field somewhere a while ago, but those were only gun turrets with a little metal plating. Why don't they build massive turrets made out of concrete and steel with giant cannons attached to them?

Because things like artillery and ground attack aircraft exist. Any fixed emplacement is a target for the gun-bunnies, and 155mm+ of high explosive says FUCK YOU to everything. It's even worse with aircraft around. Go ahead and mount fixed emplacements with enhanced sensor packages and heavy weapons. All that EM radiation and lack of movement just makes it easier for the Air Force.